<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
<script>
  let getActiveUploadObj = () => {
    try {
      return new ActiveXObject('/.../') // IE控件上传
    } catch(e) {
      return 'nextSuccessor'
    }
  }
  let getFlashUploadObj = () => {
    if(supportFlash) {
      /.../ // Flash控件上传
    }
    return 'nextSuccessor'
  }
  let getFormUploadObj = () => {
    return /.../ // Form控件上传
  }
  let getUploadObj = getActiveUploadObj.after(getFlashUploadObj).after(getFormUploadObj)
  console.log(getUploadObj());
</script>
</body>
</html>